That is a Costco guarantee on everything they sell.  In 20 years of
membership
I've only used it twice but they are absolutely great about it.  I used it
about 6
weeks ago on an item I bought 14 months prior (an item that people usually
expect lifetime wear from and the manufacturer puts a lifetime warranty on
it).
I didn't have a receipt anymore and they spent an hour looking it up.  I was
very impressed to get that kind of service from a warehouse store.  I
continue
to shop there for price, value and service.

It is indeed, the 300D (DR), and not the new 350D (DR XT).
Unlike other Canon DSLR intros of late, Canon did NOT
disco the 300D when the 350D was intro'd.

This means that Canon intends that the 300D remain the
entry-level of their DSLR line.

Yes, but it's interesting that Costco felt it necessary
to create a "bundle" in order to arrive at an appealing
price. My guess is that Canon wouldn't allow them to
simply drop the retail price of the stand-alone basic kit
below some co-marketing agreement/kickback guideline level.

Which is not to say that a spare BP511 is gratuitous.
It's a very sensible thing to buy with a new 300D.

Since the body-only is even cheaper, I'd expect the
usual suspects to be offering all sorts of low-ball
bundles, including some with 3rd-party EF lenses,
3rd-party batts, misc CF cards, etc. Caveat emptor.

18 months ago, someone mused approximately "I suppose in
10 years I'll kick myself for buying a 300D", to which I
responded, "No, you'll only kick yourself for having
spent $1000 for it. It will remain a very useful camera."

I would not be at all surprised if the typical street
price of the 300D kit hits US$500 or less before the
cam is discontinued.